Composition and method for the treatment of acne

ABSTRACT

Compositions containing organic peroxides are effective for the treatment of acne. Decomposition of the organic peroxide during storage is prevented by the incorporation of glycerol which is sufficiently effective so that decomposition is prevented even in those peroxides which are so unstable as to be explosive.

BACKGROUND OF THE INVENTION

Acne vulgaris affects virtually all youngsters beginning at the age ofabout 13 years and continuing through the age of 23 years. In femalesthe onset may occur at an age as early as 10 or later on in the 20's or30's. As is evident from all of the media, this affliction issufficiently frequent and the mental suffering, particularly,sufficiently severe so that many companies vie for the resultant marketfor appropriate medications. The number of anti-acne products sold overthe counter and by prescription is enormous.

Many compounds and compositions have been tested and prescribed for thedisease and a number have been fairly effective, but, as yet, there hasbeen no complete cure for acne.

Therapy is extremely important since if acne is left untreated, cystsform which result in permanent pitting and disfiguring scarring.Moreover, since acne is a disease primarily of adolescence, when thesufferers are most uncertain of themselves in their new roles, theattendant stigma, both supposed and real, can be the source of severepsychological trauma.

There appears to be no doubt but that the increased flow of hormones atthe onset of and during adolescence is the primary etiologic agent,since these hormones increase the size of the sebaceous glands andincrease the secretion produced by these glands. However, no correlationhas been found between the amount of endogenous serum hormone levels andthe severity of acne in the individual.

The sebaceous glands which are present in the dermal layer of the skinproduce sebum. These glands are concentrated particularly on the face,upper torso including both the chest and back, and on the scalp.Susceptibility to acne is usually greatest on the nose and on the face.

As the sebum is produced it normally flows slowly onto the surface ofthe skin. When the ducts through which the sebum flows are blocked, thesebum cannot reach the surface of the skin so that pressure builds up inthe ducts and the ductal wall ruptures, allowing the sebum to seep intothe skin's dermal layers, causing inflammation. Applying pressure to theinflamed area spreads the sebum into the dermal tissue and spreads theinflammation over a wider area.

The sebum is broken down by microorganisms which are normally present inand on the skin, the principal microorganism being C. acnes. Thismicroorganism produces lipase enzymes which hydrolyze the triglyceridesof the sebum, forming the free fatty acids which are responsible for theexternally visible comedones. The plug formed when a sebaceous duct isblocked is called a "comedo". The comedo itself is a noninflammatorylesion consisting of lipid and keratin. The lesions may initiate aspapules which in turn may evolve into pustules. However, the lesions mayalso be in the form of deeper nodules which enlarge into cysts.

Diet was originally considered to be one of the principal factorsresponsible for acne, the other being a lack of complete cleanliness.Chocolate was frequently considered the major villain, but recentstudies have shown that neither strict prohibition of suspected foodsnor strict hygienic cleansing of the skin gives the desired eliminationof acne.

With the recognition of the fact that bacteria were responsible,treatment with antibiotics became popular, tetracycline being the drugof choice. However, the degree of improvement produced by the use of anyof the antibiotics was so small that it was frequently unrecognizable.Treatment with sulphur lotions has a long history but, again, thismaterial by itself failed to produce substantial improvement of thecondition.

Complicating this situation has been the fact that young women,particularly, resort to the use of cosmetics, many of which, despiteclaims to the contrary, proved to be severely comedogenic. Increase inthe severity of the acne caused by cosmetics then leads to the use ofsimilar materials as covering agents, further exacerbating thecondition.

A. M. Kligman in work carried out in cooperation with James E. Fulton,Jr. discovered that peeling of the skin induced by topical applicationof Vitamin A acid, also called retinoic acid was beneficial in thetreatment of acne, and U.S. Pat. No. 3,729,568 issued to Kligman in1973. Approximately simultaneously, the effect of topical application ofbenzoyl peroxide was also investigated and it was found that thetreatment was relatively effective. U.S. Pat. No. 3,535,422 entitled"Stable Benzoyl Peroxide Composition" issued to Richard M. Cox andLeonard R. Clufo in 1970.

The effectiveness of benzoyl peroxide in the treatment of acne proved tobe a function of the stability of the composition applied to theaffected region. Cox et al taught that dispersing benzoyl peroxide in afluid medium consisting only of water and organic emollients produced asubstantially inert, stable composition. This stability is necessary ifthe product is to have a reasonable shelf-life, either in the pharmacyor in the family medicine chest. However, as will be shown below,benzoyl peroxide compositions prepared in accordance with any of theformulations heretofore available decompose rapidly during storage.Decomposition of the benzoyl peroxide when in contact with the skin isdesirable since it is the oxidizing effect of the free radicals producedon decomposition which provides the desired effect. However,decomposition during storage severely reduces the effectiveness of acomposition which is prepared so that it has initially the optimumconcentration.

As is evident, then, a composition in which the benzoyl peroxide isstable during storage and yet decomposes readily on contact with theskin would be highly desirable, as would be a method of treatment basedon such a composition. Moreover, other organic peroxides have also beenfound to be effective for the treatment of acne and some of these areeven more unstable during storage than is benzoyl peroxide. It wouldalso be desirable that a means of contributing stability of suchperoxides during storage be provided.

SUMMARY OF THE INVENTION

A medium for the dispersion of organic peroxides contains glycerol as aninhibitor against the decomposition of such peroxides during storagebetween the time of dispersing the peroxide in the medium to form acomposition and the time of use of said composition. For certain uses itis also desirable that a gelling agent be included in the composition,the preferred form of the composition being a soft gel or grease. Theviscosity of the composition should be such that it can be applied withthe finger to form a thin film on the skin which can readily be wipedoff after remaining in contact with the skin for a prescribed period.The preferred gelling agent is Carbopol 940, a carboxyvinyl polymerhaving a molecular weight of about 4,000,000 manufactured by B. F.Goodrich Company said resin being highly ionic and slightly acidic andsoluble. When this gelling agent is used the pH of the compositionshould be adjusted with alkali to about 4. Compositions containing aperoxide and glycerol as the stabilizer may also take the form oflotions or soaps, such compositions being useful as surgical scrubs.

The content of organic peroxide in the composition may range from 10 to300 grams per liter of composition. The preferred range ofconcentrations, the preference being based on effectiveness, is fromabout 100 grams to 200 grams per liter of composition. The glycerolcontent may range from 50 to 500 ml per liter. With the glycerol may becombined up to 200 grams of propylene glycol per liter.

Sulphur may also be incorporated with advantage in the organic peroxidecomposition, the quantity of sulphur used being from 10 to 300 grams perliter of composition.

A preferred method of treatment is the application of the composition tothe affected area once per day with the removal of the composition fromthe skin when a feeling of irritation is noted. Application of retinoicacid to the skin between applications of the organic peroxidecomposition may also prove advantageous in certain cases.

Certain of the peroxides are so unstable that they can be stored andshipped only under refrigeration. Dispersing of these peroxides inglycerol yields a composition in which the peroxide is sufficientlystable so that the composition can be shipped.

Accordingly, an object of the present invention is a compositionsuitable for the treatment of acne of all grades of severity, thecomposition containing an organic peroxide and an inhibitor againstdecomposition of said peroxide, said composition being useable as suchor modifiable to form a lotion or a soap effective for surgical scrub.

A further object of the present invention is a composition suitable forthe treatment of acne, said composition including an organic peroxide,an inhibitor against the decomposition of the peroxide and sulphur.

A significant object of the present invention is a highly effectivemethod of treating acne.

An important object of the present invention is a method of preparing acomposition for the treatment of acne where the composition includes anorganic peroxide and an inhibitor for stabilizing said organic peroxide.

Still another object of the present invention is a composition includingan organic peroxide and an inhibitor against decomposition of saidperoxide, wherein said composition is sufficiently stable to permitshipment of same.

Still other objects and advantages of the invention will in part beobvious and will in part be apparent from the specification.

The invention accordingly comprises the composition possessing thefeatures, properties and the relation of constituents which areexemplified in the following detailed disclosure, the several steps andthe relation of one or more of such steps with respect to each of theothers in the manufacture of said composition, and the several steps andthe relation of one or more of such steps with respect to each of theothers in the method of use of said composition, all of which areexemplified in the following detailed disclosure, and the scope of theinvention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the invention, reference is had to thefollowing description taken in connection with the accompanyingdrawings, in which:

FIG. 1 is a graph of the concentration of C. acnes of the skin as afunction of the fraction of free fatty acid in fatty esters in thesebum;

FIG. 2 is a graph showing the stability of benzoyl peroxide in varioussolvent vehicles at 45° C.; and

FIG. 3 is a graph showing the stability of various commercial benzoylperoxide formulations at 45° C., the stability of said commercialformulations being compared with a formulation in accordance with thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Benzoyl peroxide, used for the treatment of acne, was originally viewedas a skin irritant causing peeling in much the same way as does retinoicacid. However, I have found that when areas affected with acne aretreated in accordance with the present invention both the count of C.acnes and free fatty acid in the sebum are reduced. Since it is thebacteria which are responsible for the production of free fatty acid itis evident that benzoyl peroxide as well as other organic peroxides,both alkyl and acyl, when applied as taught herein, reduce the severityof or eliminate once by sterilization of the pores.

The analysis of sebum was carried out in accordance with the proceduredescribed in the paper entitled "Sebum: Analysis by InfraredSpectroscopy" by Arthur S. Anderson and James E. Fulton and published inthe Journal of Investigative Dermatology Vol. 60, No. 3 pages 115-120.

FIG. 1 shows the relationship between the content of free fatty acid insebum and the concentration of C. acnes in skin. This Figure is takenfrom the paper entitled "Studies on the Mechanism of Action of TopicalBenzoyl Peroxide and Vitamin A Acid in Acne Vulgaris" by James E.Fulton, Jr., A FarzadBakshandeh and Sara Bradley and published in theJournal of Cutaneous Pathology 1974, volume 1, pages 191-200. Theabcissa in FIG. 1 is actually the rate of production of C. acnes persquare centimeter of skin and the ordinate is the ratio of free fattyacid, FFA to fatty esters in the sebum, FE. Since C. acnes is primarilyresponsible for the lesions on the skin, it can be seen that the ratioFFA/FE correlates directly with the concentration of C. acnes of theskin. Further, since topical application of benzoyl peroxide and otherorganic peroxides quickly reduces the concentration of the bacteria, itis therefore evident that the organic peroxides function in thealleviation and cure of acne by sterilization of the skin.

I have found that compositions prepared as described below are effectivein the alleviation and cure of acne.

A vehicle is prepared which contains an inhibitor against thedecomposition of organic peroxide, the inhibitor being glycerol. For thepreparation of one liter of a composition including dispersed organicperoxide, the quantities of ingredients in the vehicle are 50 to 500 mlof inhibitor, 0 to 200 ml of propylene glycol, 1,2-propanediol being thepreferred propylene glycol, and water in an amount needed to bring thetotal quantity of the composition up to one liter.

The base to be combined with the above vehicle to prepare a liter ofdispersion of organic peroxide may contain from 10 to 300 grams oforganic peroxide, preferably benzoyl peroxide.

Preferably, the dispersion is thickened to the consistency of a soft gelor grease. Appropriate thickeners are finely divided silica, also knownas "Fumed Silica", magnesium aluminum silicate and Carbopol 940,manufactured by B. F. Goodrich. Carbopol 940 is a carboxyvinyl polymerhaving a molecular weight of about 4,000,000. The base should alsocontain sufficient alkali to bring the pH of the composition to a valuebetween 3.5 and 5.0, the range from 3.5 to 4.0 being preferred. Wherebenzoyl peroxide is used as the organic peroxide, this is added in theform of pellets, the commercial preparation containing 78% benzoylperoxide and 22% water. Following is a sample composition which may beregarded as the basic composition from which others are prepared byadjustment of the quantities and nature of ingredients.

    ______________________________________                                                                Concen-                                                                       tration                                                                       Range                                                 ______________________________________                                        I. VEHICLE:                                                                             H.sub.2 O      600 ml.  q.s.                                                  Glycerol       200 ml.   50-500                                               Propylene Glycol                                                              (1,2-propanediol)                                                                             50 ml.   0-200                                                               850 ml.                                              II. BASE: 78% Benzoyl Peroxide                                                                         128 gm.    1-30%                                               Carbopol 940    7 gm.    .5-2%                                                1N NaOH         5 gm.   1 ml to 20 ml                                            Makes    1 liter.                                                ______________________________________                                    

The benzoyl peroxide is added to 600 ml of the vehicle in a high-shearblender, and agitated for several minutes until dispersion is completeand the product is uniform. The Carbopol 940 is dissolved in 200 ml ofthe vehicle and this solution is then added to the benzoyl peroxidedispersion. Agitation is continued until the lotion is smooth, afterwhich the NaOH in the form of a 1N solution is added, blending beingcontinued until the resultant soft gel is homogenous. The gel can bepackaged in plastic tubing, or in resin-lined aluminum tubing. Due toits acidic nature it cannot be packaged in unlined metallic tubing.

As will be evident, the quantities given above can be increased andbatches of any desired size can be manufactured according to theprocedure described.

Additional ingredients may also be incorporated in the composition.Sulphur, particularly, has been found advantageous in certain cases. Thequantity of sulphur added may be up to about 300 grams per liter ofdispersion, about 10 grams per liter being the minimum effectivequantity. Iron oxide, or other pigments may be added to give color tothe composition. Alternatively, a composition may be prepared similar tothat given above except for the content of organic peroxide. Instead,iron oxide or other pigment is added to give a desired color. Such acomposition is termed a "cover-up". It may be used in combination withthe peroxide composition to disguise the presence of the peroxidecomposition on the skin. The advantage of the composition combiningstabilized peroxide with colorant is that it serves as a cosmetic whichcan be kept on the skin throughout the day, the peroxide content beingadjusted to correspond to the tolerance of the patient.

It is believed that the action of the glycerol is to reduce thesolubility of the peroxide in the vehicle. As a result of the fact thatthe solubility of the peroxide is reduced, the rate of decomposition ofthe peroxide in the composition during storage is greatly decreased.Studies have been carried out comparing the rates of decomposition ofbenzoyl peroxide in various solvents. The results are shown in FIG. 2,the tests having been carried out at 45° C. to accelerate thedecomposition. As can be seen at the end of 4 weeks, virtually all ofthe benzoyl peroxide in a composition within the scope of the presentinvention and manufactured by AHC Pharmaceutical Inc. remains intact. Incontrast, only about 7% of the benzoyl peroxide remains after thisperiod of time when the benzoyl peroxide is mixed with ethanol.Propylene glycol alone, as the solvent, decomposes the benzoyl peroxideeven more rapidly for the first two weeks, after which the decompositionsubstantially stops, about 27% of the original benzoyl peroxideremaining. The rate of decomposition is substantially slower in water,about 52% of the benzoyl peroxide remaining after 4 weeks at 45° C. Brij30, referred to in FIG. 2, is the trade-name forpolyoxyethylene-4-lauryl ether.

Since the organic peroxide appears to be of limited solubility in thevehicle taught herein, the resultant composition may be referred to as a"dispersion". However, it is to be recognized that the invention is notlimited to the mechanism proposed herein or by the terminology used,since some of the organic peroxide is undoubtedly soluble in thevehicle. The use of the term "dispersion" is followed because ofconvenience and is not intended to indicate the state of the organicperoxide in the vehicle.

That the combination of an organic peroxide with an inhibitor such asglycerol has practical effectiveness from the standpoint of stabilitycan be seen from FIG. 3 which provides the results of storage tests at45° C. carried out on a number of commercial formulations all of whichinitially have 10% of benzoyl peroxide therein. Compared with thesecommercial preparations is a formulation prepared in accordance with thepresent invention, and indicated as AHC Formulation 10. As can be seenfrom FIG. 3, all of the commercial preparations show serious losses ofactive benzoyl peroxide after 6 weeks of storage at 45° C. whereas thecomposition containing 10% of benzoyl peroxide and formulated inaccordance with the present invention retains about 98% of the initialbenzoyl peroxide after the 6 weeks storage period.

A substantial number of organic peroxides are presently available, aparticularly desirable organic peroxide being the succinyl peroxide.Succinic acid, while somewhat less effective than benzoyl peroxide inthe treatment of acne, has a major advantge in that the small percentageof individuals who are allergic to benzoyl peroxide are not similarlyallergic to succinic acid. The reason that benzoyl peroxide may beallergenic is that the benzoyl radical formed in a hapten, haptens beingsubstances which attach to a protein molecule and form an antigen.However, succinic acid is a normal constituent of the body in variousbiochemical processes and specifically in those concerned with theproduction of energy. Consequently, the succinic acid radical which isformed is not a hapten and thus the danger of sensitization orallergenic reaction is completely avoided. Lauryl and cumyl peroxideshave also been found to be effective though not as effective as benzoylperoxide.

Surfactants can be included in stabilized benzoyl peroxide compositionswithout impairing the stability thereof. Following is a compositionwhich is a lotion, effective as a surgical scrub, and which is amodification of the basic composition presented above.

    ______________________________________                                        LOTION                                                                        ______________________________________                                        Distilled Water         550 ml                                                Glycerol                200 ml                                                Propylene glycol        100 ml                                                Benzoyl Peroxide (78%)  32 gm                                                 Carbopol 940            15 gm                                                 Stepanol                40 gm                                                 Sodium Lauryl Sulfate   40 gm                                                 Sodium Hydroxide 3 N    20 gm                                                 ______________________________________                                         Note: Stepanol is a sodium alkyl sulfate manufactured by Stepan Corp. of      Illinois.                                                                

The benzoyl peroxide content in the above lotion formulation is 2.5%. Asis evident, the concentration of peroxide and of the other componentscan be varied, as can the peroxide used, in ways apparent to thoseskilled in the art.

Benzoyl peroxide, stabilized with glycerol may also be added to aconventional soap to provide benefits similar to those which accrue fromthe use of the compositions already taught. More particularly, a soapcontaining up to about 10% of a peroxide and containing glycerol in aratio to the content of said peroxide similar to the ratios in thecompositions taught above is an effective surgical scrub. Benzoylperoxide is the preferred peroxide because of its relatively low costand high effectiveness. Where compounds which may react with an organicperoxide are present in the soap stock to be combined with peroxide andglycerol, such compounds should be removed as by conventional meansprior to formulation.

A formulation suitable for a surgical scrub soap contains about 1% toabout 20% by weight of an organic peroxide, preferably benzoyl peroxideand sufficient glycerol to stabilize the peroxide. Propylene glycol maybe incorporated in the soap if desired, as may conventional soapbuilders.

The number of gelling agents which can be used is substantial, virtuallyany water-soluble polymer of sufficiently high molecular weight beingappropriate. Carboxymethyl cellulose has been tested and found to bequite effective. Magnesium aluminum silicate and fine silica aspreviously noted can also gel the solution. However, the quantity offumed silica necessary to obtain the same increase in viscosity providedby a given quantity of Carbopol 940 is about 10 times as great.

Therapy with benzoyl peroxide is preferably commenced slowly; forexample the dispersion should be allowed to remain on the skin or 3 to 4hours daily. The initial burning sensation subsides rapidly after thefirst few weeks and exposure time can be increased. Where the patient issufficiently sensitive so that irritation is excessive to the pointwhere it may be termed "toxic", the condition is rapidly reversiblewithin a day or two after interruption of treatment. Therapy can thenrecommence. Over 3-4 weeks, the skin becomes hardened and accommodatedto the treatment. As the patient becomes more accustomed to the use ofthe peroxide, the concentration and frequency of application may begradually increased to the level required to maintain control. Althoughconcentrations as high as 30% in benzoyl peroxide and 30% in sulphur maybe utilized, the maximum concentration is preferably 20% for benzoylperoxide and 10% for sulphur. Tests have shown that the addition ofsulphur in this concentration to benzoyl peroxide definitely increasesthe efficacy of the composition.

In clinical studies, improvement is readily ascertained from thedramatic change in the total lesion count. In carrying out tests andevaluating the results of same, the lesions are graded by arbitrarystandards from grades I through IV with grade IV being the most severe.

                  TABLE I                                                         ______________________________________                                        TOTAL LESION COUNT AT                                                         TWO WEEK INTERVALS DURING TREATMENT                                           FIRST CLINICAL STUDY                                                                               2       4     6     8                                    Group &      Initial Week    Week  Week  Week                                 Medication   Visit   Visit   Visit Visit Visit                                ______________________________________                                        Acne, Grade I & II                                                                         25.3    15.5*   15.0*  9.2   8.8                                 Benzoyl Peroxide                                                                           (22)    (22)    (16)  (5)   (9)                                  10%                                                                                        21.3    10.5*    9.1* 15.2   9.0                                              (20)    (20)    (10)  (6)   (2)                                  Acne, Grade III & IV                                                                       38.7    23.5*   17.8* 14.9* 14.1*                                Benzoyl Peroxide                                                                           (180)   (180)   (133) (78)  (60)                                 20% + Sulfur 10%                                                              ______________________________________                                         * = p<0.05                                                                    () = number of patients in each group                                    

Table I shows the results of a clinical study in which patients withacne of grades I and II were treated with a gel (dispersion) containing10% benzoyl peroxide and patients with grades III and IV acne weretreated with a gel (dispersion) containing 20% of benzoyl peroxide and10% of sulphur. As is evident, the number of lesions decreasedsubstantially during the 8-week period for the groups of patients. Infact, for the patients with acne of grades I and II, the benzoylperoxide at a level of 10% produced significant improvement within 2weeks, the improvement progressing to a controlled condition at the endof the period. A significant marked decrease was also demonstrated forthe group having grades III and IV acne which was treated with 20%benzoyl peroxide and 10% sulphur dispersion.

In a second clinical study utilizing a more confined population similarresults were obtained with a gel containing 10% benzoyl peroxide and 5%sulphur. The results are summarized in Table II.

                  TABLE II                                                        ______________________________________                                        TOTAL LESION COUNT AT                                                         TWO WEEK INTERVALS DURING TREATMENT                                           SECOND CLINICAL STUDY                                                                              2       4     6     8                                    Group &      Initial Week    Week  Week  Week                                 Medication   Visit   Visit   Visit Visit Visit                                ______________________________________                                        Acne, Grade I & II                                                                         27.4    18.9*   18.0* 17.5* 16.3*                                10% Benzoyl Peroxide                                                                       (48)    (48)    (29)  (17)  (11)                                 Benzoyl Peroxide                                                                           31.8    24.6*   28.4* 19.8*  8.0                                 10% + Sulfur 5%                                                                            (28)    (28)    (19)  (10)   (5)                                 Acne, Grade III & IV                                                                       28.2    18.8*   12.9* 12.8*  8.4*                                Benzoyl Peroxide                                                                           (50)    (50)    (28)  (19)  (14)                                 20% + Sulfur 10%                                                              ______________________________________                                         * = p<0.05                                                                    () = number of patients in each group.                                   

In general, treatment with a gel containing 20% of benzoyl peroxide and10% of sulphur shows the most consistent and dramatic reduction inlesion count.

The treatment with organic peroxide dispersion can be supplemented withtreatment with retinoic acid. Thus, if the organic peroxide gel isapplied in the morning, then retinoic acid may be applied in theevening. The retinoic acid is preferably used at a concentration ofabout 0.001% to 0.01% in a non-irritating vehicle. It should not beformulated in ethanolic solutions which are irritating to the skin whenused in conjunction with a material which tends to remove layers of theskin. A suitable vehicle for the Vitamin A acid is a low-boiling estersuch as ethyl acetate or a ketone such as acetone. An excellent responsewhich is considered synergistic is to apply the retinoic acid solutionto the skin and allow it to dry for about 10 minutes, after whichbenzoyl peroxide gel is applied directly over the Vitamin A acid.

A number of the organic peroxides are known which are sufficientlyunstable so that they must be refrigerated. Others are so unstable thatthey may explode. Obviously, both of these types of compounds presentdifficulties with respect to shipment and use. I have found thatdispersion of these organic peroxides in glycerol solution renders thesecompounds sufficiently stable so that they may be shipped withoutrefrigeration and without presenting the danger of explosion.

A particular advantage of the compositions described herein for thetreatment of acne and of the treatment mode described is that the courseof treatment requires the presence of a physician only intermittently.In general, a nurse can readily be trained to discern the progress ofthe treatment and whether a condition has arisen which requires theskill of a physician. Consequently, the extended treatment involved inalleviation of acne is made substantially less expensive than would bethe case were it necessary for each application of the medicament to bemade under the observation of a physician.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained, and,since certain changes may be made in carrying out the method ofmanufacturing the various products and in the compositions set forthwithout departing from the spirit and scope of the invention, it isintended that all matter contained in the above description and shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

What is claimed is:
 1. A composition, comprising a dispersion of about10 weight % of benzoyl peroxide in an aqueous solution containing about20 volume % glycerol to inhibit decomposition of said peroxide, saidcomposition being effective in the treatment of acne.
 2. The compositionas claimed in claim 1, further comprising sufficient gelling agent toincrease the viscosity thereof to that of a grease.
 3. The compositionas claimed in claim 1, wherein said composition further contains 5 to100 grams of gelling agent per liter.
 4. The composition as claimed inclaim 3, wherein said gelling agent is selected from the groupconsisting of carboxymethyl cellulose, magnesium aluminum silicate,finely-divided silica and carboxyvinyl copolymer.
 5. The composition asclaimed in claim 1, in combination with sufficient alkali to bring thepH of said dispersion to between about 3.5 and 5.0.
 6. The compositionas claimed in claim 1, wherein said gelling agent is carboxyvinylcopolymer in a concentration range of 5 to 20 grams per liter of saidcomposition.
 7. The composition as claimed in claim 1, furthercomprising from 10 to 300 grams of finely-divided sulphur per liter ofsame.
 8. The composition as claimed in claim 1, further comprising aneffective amount of a surfactant compound.
 9. The composition as claimedin claim 1, further comprising a coloring amount of a pigment.
 10. Amethod of treatment of acne, comprising the step of applying topicallyto an affected area a composition comprising an aqueous dispersion of anorganic peroxide effective in the treatment of acne, each liter of saidcomposition comprising about 100 grams of benzoyl peroxide, about 200 mlof glycerol, from 0-200 ml of propylene glycol and water, said stepbeing repeated until a desired decrease in severity of said acne isachieved.
 11. The method as defined in claim 10, wherein each liter ofsaid composition further comprises 5 to 100 grams of gelling agent. 12.The method as defined in claim 11, wherein said gelling agent is amember selected from the group consisting of carboxymethyl cellulose,magnesium aluminum silicate, finely-divided silica and carboxyvinylcopolymer.
 13. The method as defined in claim 11, wherein said gellingagent is carboxyvinyl copolymer in an amount of 5 to 20 grams per literof said composition.
 14. The method as defined in claim 10, wherein eachliter of said composition contains alkali in an amount such that the pHof said composition lies between about 3.5 and 5.0.
 15. The method asdefined in claim 10, wherein each liter of said dispersion furtherincludes 10-300 grams of finely-divided sulphur.
 16. The method asdefined in claim 15, further comprising the step of applying retinoicacid to said affected area at a time of day when said affected area isessentially free of said dispersion.
 17. The method as defined in claim10, wherein said dispersion is applied daily and allowed to remain onsaid affected area for a period up to about 6 hours, said period beingcommensurate with the resistance of the skin to irritation by saiddispersion, and comprising the step of removal of said dispersion.
 18. Asurgical scrub soap, comprising about 10 weight % of benzoyl peroxide,and about 20 volume % of glycerol to stabilize said peroxide, said soapbeing free of ingredients reactive with said benzoyl peroxide.